The present invention relates to a structural joint for slabs made of a moldable material, particularly for slabs made of a material having a hydraulic binding agent, such as concrete.
When large concrete surfaces are to be made, it is recommended to divide the surfaces into concrete slabs of a given size. Advantages are obtained from providing, between these slabs, on the edges thereof, metal elements named structural joints allowing, on the one hand, thermal contraction or expansion as well as correction of dimension or angle variations, and on the other hand reinforcement of the edges of the moldable material with a hydraulic or non-hydraulic bonding agent, e.g. concrete slabs.
Currently, concrete slabs are commonly reinforced by joints made from sheet steel profiles.
Several different types of metal joints have been proposed to provide a reinforcing effect on the composite material at joint areas. This reinforcing effect essentially depends on the geometric and mechanical properties of the selected joints.
In order that different types of structural joints can be compared, it may be of use to recall the behavior and the process for reinforcement of the sharp edge of a composite fragile matrix material.
This behavior depends on the reinforcing effect on the matrix near the sharp edges submitted to scratching and shearing stress.
Reinforcement at the ends of the slabs should ideally meet the following requirements:
adequate protection of the sharp edge,
effective anchorage to prevent detachment,
a mortise and tenon system,
the need to provide sufficient thickness, to prevent slabs from being sheared at weak points, determined by the geometric design of the metal profile.
Therefore, the invention relates to a structural joint, for example made of steel, for reinforcement of the sharp edges of a matrix or slab material, e.g. concrete, which never comes loose therefrom, neither due to the joint, nor to matrix embrittlement at the anchorage area.
To this end, the reinforcement joint comprises a male and female jointing system downwardly offset from the median line of the slab, so that a greater thickness of the matrix can be obtained above the jointing system to provide higher resistance to external stress loading.
Joints of the double-profile type having a male/U-shaped female mortise and tenon system and opposing relative vertical displacements of the two half-slabs are already known in the art.
Profiles are integral with concrete slabs, by being anchored thereto by reinforced concrete rods welded on profiles.
A common structural joint is obtained from a substantially omega-shaped double profile, with the outer contour of the one fitting the inner contour of the other. The male central part of the joint must have a sufficient volume to allow it to be filled with the moldable material.
When the slab has an even thickness and the upper part of the joint has to be thickened to reach important load capacities, the lower part of the joint becomes insufficient, wherefore this lower part will no longer stand said loads due to an insufficient thickness of the matrix.
Hence, the need arises to have a number of joint models having different heights.
Another problem encountered with such profiles consists in that, when the concrete slab has a reduced height, the minimum size of the omega-shaped profile is still considerable due to the volume required for the male central part of the joint.
As a result, the concrete mass in the upper part of the slab edge, above the profile jointing system, is widely insufficient to stand normal loads on the slab surface and, consequently, this part is exposed to deterioration caused by concrete cracking or scratching.
The object of the present invention is to obviate the above drawbacks through simple and effective means, which will be described in detail below.
To that effect, the structural joint in accordance with the invention has the characteristics as specified in the claims at the end of the disclosure.